Generating and transmitting electric currents



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CROSS RE:

Original Filed April 10, 191

fllexandfif/ Aw m 7111 mini Patented Aug. 27, teen 2,2l2,di

rarest caries GENERATING AND TRANSMITTING ELECTRIC CURRENTS Alexander M. Nicolson, New York, N. Y., assignmto Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Original application April 10, 1918, Serial No. 227,862, now Patent No. 1,405,429, dated May 29, 1924. Divided and thisfipplication April 13, 1923, Serial No. 631,859

55 Claims.

This invention relates to piezoelectric translating devices and has for an object to utilize piezoelectric eflects in the generation of electric oscillations and also in the modulation of alternating 5 currents by signal waves or the like.

In the form of the invention disclosed herein.

a piezoelectric crystal having a plurality of electrodes is used as a coupling means between the output and input circuits of a vacuum tube amplifler. Sufilcient energy is transferred through this coupling to cause the circuit to generate oscillations. As will be explained hereinafter, the crystal has certain frequency selective characteristics which enable it to determine the frequency of the oscillations.

Due to the fact that a piezoelectric body generates electricity in response to pressure changes, the oscillations above described may be modulated by mechanically stressing the crystal. As shown, the crystal is provided with a surface adapted to be vibrated by sound waves, and means is provided in the output circuit of the vacuum tube for utilizing the sound frequency modulated oscillations. This application is a division of application Serial No. 227,802, filed April 10, 1918, entitled Plezophony which issued as Patent 1,495,429,

May 29, 1924.

Further objects of the invention will be epparent from the following detailed description and claims taken in connection with the accompanying drawing, in which the single figure is a diagram of an oscillator and modulator circuit embodying the invention.

The piezoelectric body employed in this invention may be, for example, a sodium-potassium tartrate crystal or other piezoelectric crystal body, and is designated ii in the drawing. In my Patent No. 1,414,370, May 2, 1922, Method of I making piezoelectrical crystals, there is described a method of preparing a thin, or plate-shaped crystal in which the piezoelectric effect is very pronounced.

The electrical resistance as well as the natural frequency of the crystal made in accordance with that process depends upon the amount of moisture that is permitted to enter or leave the crystal, and therefore, as pointed out in the patent referred to, in order to stabilize the electrical constants of the crystal it may be provided with a waterproof coating such as am'broid or wax.

The showing of the crystal 4? in the drawing is anedge view of a plate-shaped crystal such as that referred to above. Members Band I having extended surfaces and being formed of Wood's metal, which has a melting point about the same as that of the crystal, may be soldered to the crystal, a conductor as being soldered to the member 7 to form an electrical connection to the crystal; Electrical con- 5 nections are also made to the crystal by means of the conductors 48 and Si which are attached by means of Wood's metal or other fusible alloy to tin foil sheets i0 and I I cemented with ambroid to the opposite sides of the crystal. 10

If varying currents are supplied to the input conductors 49 and 51 of the piezoelectric crystal 41 the current variations will produce longitudinal contractions and expansion of the crystal, and these variations in the dimensions of the 15 crystal will produce correspondingly varying electric currents in the output conductors 4B and 49 of the crystal. The crystal is a dielectric, current through the crystal being largely a dis placement current.

It Has been found that a crystal made as indicated above responds in a greater degree to-currents of some frequencies than to currents of other frequencies. Each such crystal will in general have a plurality of resonant peaks depend- 25 ing upon the crystal's growth, structure, curing, etc. In some crystals all of the resonant peaks have been found to lie in a zone of 300 to 10,000 cycles per second, and in others this zone may lie above 10,000 and extend to 100,000 cycles per 30 second.- It. is'possible to modify thposition'oi the zone of resonance points for instance by varying the period of desiccation of the crystal. The longer the cryisal is desiccated, the higher up in the scale will the zone of resonant peaks lie. 35 Of course, the masses of the members 6 and l affect the value of the frequency of maximum response 'of the crystal.

Connection is made from device 41 by way of conductors 48 and 49 to the input circuit of a space current amplifier 58, and a portion of the amplified currents appearing in the output circuit oi the amplifier are fed back by means of conductors 49 and 5| to the device 41. Since the input and output circuits of the audion are coupled togetherthrough the device ll, this circuit will generate oscillations and their frequency will be suificiently high for these currents to be 'em-- ployed as carrier currents for radio signaling or for wired wireless. The frequency of the ,oscilo lations will in general be determined by one of the resonant peaks of the crystal. It is" not to be implied from this statement, however, that the circuit may not be made to oscillate at some other frequency, for example by the proper use 55 g 2 of reactances, of which the reactance of the crystal may form a part.

In one method of using the circuit, signal or sound waves may be caused to impinge upon the extended surface of the member 6, attached to the piezoelectric crystal 41, as indicated by the dashed line arrows in the drawing, to eflect modulation of the high frequency oscillations in accordance with the signal or sound waves. The amplitude of the high frequency current generated having thus been varied in accordance with the sound waves, the modified high frequency impulses may be delivered to the outgoing line 52.

The term piezoelectric means is used herein to indicate means comprising a body, device, or substance capable of generating an electromotive force in response to a change in pressure, independently of any source of electromotive force apart from that so generated.

-The invention may be realized in widely different embodiments within the scope of the claims.

The invention claimed is:

1. An oscillating circuit comprising a piezoelectric device.

2. An amplifier, a piezoelectric device, and means controlled by said device for deriving energy from said amplifier and feeding said energy back to said amplifier.

3. A space current device having an input circuit and an output circuit, and means comprising a piezoelectric device for coupling said circuits together.

4. A system for generating continuous oscillations comprising a space current device having an anode, a cathode and ,an electrode for controlling the flow of space current between said cathode and said anode in accordance with variations of the potential of said electrode, and piezoelectric means for controlling variations of the potential of said electrode.

5. In a system in which high frequency waves are modified in accordance with a signal, means for modifying said waves in accordance with said signal, said means comprising a piezoelectric device.

6. A piezoelectric device means whereby said device may be controlled in accordance with signal waves, and means for applying high-frequency signaling impulses to said device.

'7. The method of setting the frequency of an oscillation carrying electric circuit which comprises transferring energy from one part of the circuit to another through a piezoelectric coupling mechanically tuned to substantially the frequency to which the oscillating circuit is to g be set.

'8. A frequency selective coupling for transf erring energy between two circuits, said coupling comprising a. piezoelectric device mechanically tuned to the frequency of the energy to be transmitted.

energy back into said amplifier, said element undergoing deformation when alternating voltage is applied thereto. and the dilations reaching a maximum, for constant values of voltage, when the frequency cf.the applied voltage coincides with the elastic natural frequency of the element.

11. An oscillation carrying circuit comprising a reactive element including an elastic structure the natural elastic vibration frequency of which is substantially the oscillation frequency of said circuit, said structure comprising a dielectric body provided with electrically conducting condenser armatures connected in said circuit.

I 12. The method of elastically deforming a piezoelectric body which comprises simultaneously applying thereto varying electric forces and varying mechanical stresses in addition to the mechanical stresses resulting from said electric forces.

13. The combination with an alternating current system of such nature that the frequency of the alternations is governed by potential variations in a portion of the same, of a means for keeping the frequency constant within very narrow limits consisting of a piezoelectric resonator having two conducting coatings so connected to the system that the said resonator is maintained in vibration by the electric oscillations in the system, and which by its reactions causes the frequency of said potential variations to be identical with that of its own mechanical vibrations.

14. A space-current oscillator comprising me chanical vibratory means vibrating under control of output energy from said oscillator for transferring energy from the output to the input of the oscillator.

15. An oscillator comprising piezoelectric means vibrating under control of output energy from said oscillator for transferring energy from the output to the input of the oscillator. 16. An oscillation generator including a frequency controlling device, said device comprising a piezoelectric crystal, an electrode therefor, a vibratory member associated with said electrode, said member being adapted to vibrate responsively to impressed sound vibrations.

17. In combination, a thermionic device arranged to generate oscillations, a piezoelectric crystal associated with a plurality of electrodes connected to said thermionic device, and signals responsive means for altering the relation of one of said electrodes to said crystal.

18. An oscillating system comprising an input circuit and an output circuit. the system being normally non-oscillating, and a piezoelectric body connected with the input circuit and designed to render the system oscillating and at substantially constant frequency.

19. An oscillating system comprising means for producing oscillations, including a piezoelectric body designed and connected to maintain the frequency of the oscillations substantially constant.

20. An oscillatory system comprising a spacecurrent device comprising three electrodes, namely, a-filament, a grid and a plate, and a piezoelectric device connecting two of 'the electrodes,

the device being adapted'to vibrate mechanically when stimulated electrically and to respond electrically when vibrated mechanically. I

21. A piezoelectric device having a given natural frequency, an oscillator arranged to excite said device at substantially the said given frequency, and means for varying the amplitude of oscillations of said device.

22. In a carrier wave signaling system,

a piezoo 3:? no. a Cuties ho: enclose i-l iiibli 00M electric device, an oscillator ior energizing said device to cause the same to vibrate at the carrier wave frequency, and means to: modulating the vibration of said piezoelectric device.

23. In a carrier wave signaling system, a piezoelectric device arranged to vibrate at carrier wave frequency, an oscillator arranged to energize said device, and means for modulating the vibrations of said device. l

24. An oscillation generating system comprising a closed wave propagating circuit including a piezoelectric crystal element for determining the frequency of the wave propagated therethrough, an energy source, and means also included in said circuit for cyclically abstracting energy from said source and feeding it into said circuit at a natural vibratory frequency of the crystal elemen 25. An oscillation carrying circuit comprising a piezoelectric device consisting of a piezoelectric crystal and conducting electrode elements therefor.

26. An oscillation carrying circuit comprising a device consisting of electric field producing means comprising electrode members and having in the electric field between said members a piezoelectric crystal.

, 2'7. In a circuit carrying electrical oscillations, a device consisting of metallic plates having between them a piezoelectric crystal.

28. In a circuit carrying electrical oscillations, a device consisting or metallic plates having between them and attached thereto a piezoelectric crystal. l

29. An electro-mechanical system having, in combination, a vacuum tube having three electrodes, namely, a filament, a grid and a plate, an electromechanical vibrator having a plurality of electrodes, means connecting one of the vibrator electrodes to the grid, means connecting another vibrator electrode to the plate. and connections whereby the system is adapted to oscillate with the frequency of a mode of vibration of the electromechanical vibrator and widely independent of the electrical constants of the system.

30. An electric system having, in combination, an input circuit, an output circuit coupled to the input circuit, the electrical parameters of the circuits-being such as to render the system per se stably non-oscillatory, and an'electromechanical vibrator connected in the input circuit to cause the system to oscillate at a frequency of a mode of vibration of the vibrator, the input circuit being substantially untuned except through the vibrator.

31. An oscillatory system having, in combination, an amplifying relay having a plurality of electrodes, a source oi. energy, on electromechanical vibrator means connecting the relay," the source and the vibrator together to constitute an oscillatory system, the electrical parameters oi the oscillatory system being such asto render the oscillatory system stably non-oscillatory when not under the control of the vibrator,

--whereby the frequency 01 the oscillations of the oscillatory system when the oscillatory system oscillates will be substantiallyconstant and 'de-' termined by a mode of vibration of the vibrator,

. a winding connected with two oi the electrodes, and means connected with the'winding for transmitting electric wave energy from the system.

32. An oscillatory system having, in combinatlon, an amplifying relay, 9. source oi energy, an electromechanical vibrator, means connecting .726 the,relay. the source and the vibrator together to constitute an oscillatory system, the electrical parameters of the system being such as to render the system stably non-oscillatory when not under the control of the vibrator, whereby the irequency of the oscillations of the system when the system oscillates will be substantially constant and determined by a mode of vibration or the vibrator, a secondary circuit associated with the system. and means for adjusting one of the circuits so as to enhance the energy output of the system.

33. {in oscillatory system having, in combination, an electromechanical vibrator with at least two electric terminals-said terminals serving both for electric stimulation and electric response, a source of electric energy, an amplifying device and connections to maintain the system in vibration witha frequency widely independent oi the electrical constants of the system exclusive of the vibrator.

34. An oscillatory system having, in combination. an electromechanical vibrator with at least two electric terminals, said terminals serving both for electric stimulation and electric re sponse, a source 01' electric energy, a repeating device and connections to maintain the system in vibration with a frequency widely independent of the electrical constants of the system exclusive of the vibrator.

35. A system including a sell-oscillating vacuum tube device having a piezoelectric crystal coupling its input and output circuits.

38. An electromechanical system having, in combination, a vacuum tube having three electrodes, namely, a filament, a grid and a plate, an electromechanical vibrator connected with the filament and plate, and connections whereby the system is adapted to oscillate with a frequency determined by the electromechanical vibrator.

37. An electromechanical system having, in combination, a vacuum tube having three electrodes, namely, a filament, a grid and a plate, an electromechanical vibrator connected with the filament and the grid, and connections whereby the system is adapted to oscillate with ta. frequency determined by the electromechanical vibrator.

' 38. An electromechanical system having, in combination, a vacuumtube comprising three electrodes, nam'ely,a filament} a grid andpla'te,

an electromechanical vibrator having two electrodes, means connecting one of the vibrator electrodes to the plate, means connecting th e other vibrator electrode to the grid, and connections whereby the system is adapted to oscil late with the frequency of a mode oi vibration of the electromechanical vibrator and widely inde pendent of the electrical constants of the system. 39. An electromechanical system having, in combination, a vacuum tube each comprising three electrodes, namely, a filament-a grid and a plate, an electromechanical vibrator having two electrodes, means connecting one of the vibrator electrodes to the tube plate, means connecting the other vibrator electrode to the filament, and

connections whereby the system is adapted to 41. An electromechanical system having, in. combination, a vacuum tube having three electrodes, an electromechanical vibrator having a plurality of electrodes, means connecting one of the vibrator electrodes to one of the tube electrodes, means connecting another vibrator electrode to another of the tube electrodes, and connections whereby the system is adapted to oscillate with the frequency of a mode of vibration of the electromechanical vibrator and widely independent of the electrical constants of the system.

42. An electromechanical system having, in combination, a circuit having an inductance and an element having capacitance connected to each other and a circuit in oscillating relation to the first-named circuit having a piezoelectric element.

43. An oscillatory system having, in combination, an amplifying relay, a source of energy, an electromechanical vibrator and means connecting the relay, the source and the vibrator together to constitute an oscillatory system, the electrical parameters of the system being such as to render the system stably non-oscillatory when not under the control of the vibrator and such that the frequency of the oscillations of the system when combination, a vacuum tube comprising a plurality of electrodes, an electromechanical vibrator having a plurality of electrodes, means connecting one of the vibrator electrodes to one of the plurality of electrodes of the tube. means connecting another vibrator electrode to another of the plurality of electrodes of the tube, and connections'whereby the system is adapted to oscillate at the frequency of a mode of vibration of the electromechanical vibrator, and widely independent of the electrical constants of the systom.

45. An electromechanical system having, in

- combination, vacuum tube apparatus, a source of energy, an electromechanical vibrator, means connecting the vacuum tube apparatus, the source and the vibrator together to constitute an oscillatory system adapted to oscillate at the substantially constant frequency oil a mode of vibration of the electromechanical vibrator, the connections being such as to prevent the operation of the system at other than the said substantially constant frequency, and an impedance in series with the vibrator.

f16.AIl electromechanical system having, in combination, vacuum tube apparatus, a source of energy, an electromechanical vibrator, means connecting the vacuum tube apparatus, the source and the vibrator together to constitute an oscillatory system adapted to oscillate at the substantially constant frequency of a mode of vibration of the electromechanical vibrator, the electrical constants of the system being of such value control of the frequency, and an impedance in series with the vibrator.

4'7. An oscillatory system having, in combination, an amplifying relay having a plurality of electrodes, a source of energy, an electromechanical vibrator, means connecting the relay, the source and the vibrator together to constitute an oscillatory system, the electrical parameters of the oscillatory system being such as to render the oscillatory system stably non-oscillatory when not under the control of the vibrator, whereby the frequency oi the oscillations of the oscillatory system when the oscillatory system oscillates will be substantially constant and determined by a mode oi vibration of the vibrator, a winding connected with 'two of the electrodes, and means connected with the winding for transmitting electric wave energy to the system.

48. The method of modulation in accordance with signals by means of a piezoelectric device vibrating between two electrodes which consists in shaking the device and at least one of its electrodes in accordance with signals and simultaneously impressing upon said electrodes electrical oscillations, the frequency of which is controlled by said piezoelectric device.

49. In combination, a circuit, a piezoelectric device therein, and means whereby alternating current is caused to traverse said circuit and said device, the frequency thereof being such that the effective reactance of said device, by reason of its dynamic operation, departs substantially from that of an equivalent pure capacitance at the same frequency.

50. A circuit adapted to carry electrical oscillations and means having an energy transfer coupling therewith for impressing said oscillations thereon, said circuit comprising a piezoelectric device.

51. A frequency determiningdevice comprising as an element thereof a pie-2o electric crystal body having a selected vibrational frequency.

52. An electromechanical vibrator comprising a body of piezoelectric material adapted to be excited by an electric field to undergo mechanical vibrations of a resonance frequency of the body, the body being'so fabricated that the resonance frequency will substantially approximate a predetermined vibration frequency.

53. An electromechanical resonator prising abody of crystalline Rochelle salt, a. pair of conducting electrodes associated therewith to enable an exciting field to be impressed upon the body, the body being so made as to have a natural resonance frequency corresponding to a desired connections from said vibrator to the input of,

said amplifier for supplying impulses to theamplifler to be amplified, both said setsof connections being free from movlngloontacts.

ALEXANDER M. NICOLSON. V 

